Isothermic package

ABSTRACT

The isothermic package is comprised of a flat and flexible envelope (10) of which the two walls (11, 12) are welded along three sides so as to provide an opening (13) for introducing and withdrawing the product (P) to be kept warm or cold during its transportation. The walls (11, 12) are each comprised of two isothermic sheets (14, 15) which delimit therebetween a spaced (16, 17, 18) filled with a gas having a low heat transmission power.

There are known isothermic packages which permit maintaining during acertain interval of time hot or cold alimintary products at anacceptable temperature.

These packages are generally used for transporting a hot or cold productfrom the place where it is purchased to the place where it is consumedor the place (cold storage, refrigerator, etc.) where it is kept orstocked before being consumed.

Unfortunately, these packages do not offer a satisfactory thermicbarrier when the ambient temperatures go beyond the habitual norm or ifthe duration of the transport is relatively long.

In this case, the temperature of the product attains during thetransport a critical temperature by reason of which its appearance, itsqualities, its taste are altered in the manner that it becomes unfit forconsumption.

The present invention has for its object an isothermic package whichpermits at least doubling, all conditions and proportions being thesame, the duration during which the product is maintained at anacceptable temperature, that is to say situated above or below accordingto the case of the critical temperature.

This package which is constituted by an envelope provided with anopening for the introduction and removal of the product is characterizedby the fact that the walls of the envelope are each formed of aplurality of sheets defining between them at least one closed spacefilled with fluid. The annexed drawing represents schematically and byway of nonlimiting example a form of execution of the object of theinvention and illustrates a process of fabrication of this form ofexecution of the package according to the invention.

FIG. 1 is a plan view of the empty package.

FIG. 2 is a section along the line II--II of FIG. 1.

FIG. 3 is a section similar to that of FIG. 2 of the package containinga product.

FIG. 4 is a view of a detail.

FIGS. 5 to 9 illustrate the several operations of the process offabrication of this package.

The package shown in FIGS. 1 to 4 is constituted by a flat soupleenvelope 10 of rectangular form of which the two walls 11 and 12 arewelded on three sides in a manner to provide an opening 13 for theintroduction and removal of the product.

Each of the walls 11 and 12 is composed of two sheets 14,15 whichconfine between them pockets 16 and 17 filled with air or a gas havinglow power of transmission of heat and a pressure slightly greater thanatmospheric pressure.

The pockets 16 and 17 are connected with one another at a side oppositethe opening 13 by a passage 18.

The sheets 14 and 15 which are found in commerce are constituted by alayer of plastic material 19 and by a metalized layer 20.

The product to be transported is introduced into the package into thepackage through the opening 13 then the envelope is rolled beginningwith this opening until the product is well held, then the rolled partis fixed with one or two clips possibly with closure means incorporatedor not in the package, these means been given a pretensioneddisposition.

In the course of rolling, the thickness of the layer of air is increasedmore or less according to the volume of the product.

The thermic barrier formed by this layer of air and by the doublethickness of the walls themselves, constituted by the isothermic sheetspermits maintaining during several hours temperatures in theneighborhood of the temperatures of conservation of the producttransported or stocked.

It is remarked that by virtue of the passage 18, the continuity of thisthermic barrier is not interrupted at the bottom of the package. This isparticularly important due to the fact that the bottom of knownisothermic packages is generally the place where the heatexchanges--from the exterior to the interior or inversely--are greatest.

In a variant, the air contained in the spaces 16, 17 can be replaced bya liquid, advantageously, a liquid called refrigerant analogous to theliquid utilized in souple "ColdHo Pack" pockets of 3M of which thecongealing point is of the order of -18° C.

The isothermic packages thus realized can be stocked in refrigeratedenclosures before being used in a manner to permit sensibly, prolongingthe duration during which the product is conserved at an acceptabletemperature.

The process of fabrication of the package illustrated in FIGS. 5 to 9 isespecially economical.

The process consists starting with two rectangular sheets of the typeshown in FIG. 4 of which one A is longer and wider than the other B(FIG. 5) superposing the two sheet, plastic layer against plastic layerand making their small sides coincide and forming an undulation C toabsorb the excess length of the sheet A (FIG. 6) heat welding the twosheets along the bands D FIG. 7, pressing down one against the other thetwo portions of the two sheets thus welded (FIG. 8) heat-welding thecorresponding borders E of the sheet A, inflating during this lastoperation air or an appropriate gas in the pockets 16 and 18 duringformation.

In a variant of this process, the operations of welding (FIGS. 7 and 9)can be combined in a single operation after having pressed together insuitable positions the two sheets A and B (FIG. 8).

I claim:
 1. An isothermic package comprising two rectangular sheets offlexible plastic material, namely an inner sheet and an outer sheet,said outer sheet being longer than said inner sheet to provide excessmaterial in said outer sheet, said sheets being sealed together at theirmargins with fluid trapped between them to form a hollow double wallstructure,said double wall structure being folded along a transverseline to bring opposite ends together and being sealed together alongopposite side edges to form a pocket for receiving an item to bepackaged, said excess material of said outer sheet providing anundulation at the fold to provide communication between opposite hollowwalls of said package, and said opposite ends of said double walls beingsuperposed and separable to provide an entry way for an item into saidpackage and being foldable or rollable to close said entryway and toincrease pressure of fluid in said hollow double walls of said package.2. An isothermic package according to claim 1, in which a surface ofsaid sheets of plastic material is metalized.
 3. An isothermic packageaccording to claim 1, in which said fluid is a gas.
 4. An isothermicpackage according to claim 1 in which said fluid is liquid refrigerant.